The Research On Heterogeneous Ion Doped Into Rare Earth Upconversion Luminescent Nanomaterials And Their Morphology Controlled And Luminescence Optimization

Rare earth upconversion luminescent nanomaterials is a kind of anti-Stokes luminescent material which can convert low energy photon into high energy photon based on its multi-photon process and energy transfer mechanism.Compared with the traditional luminescent materials,the rare earth upconversion luminescent nanomaterials have the advantages of good optical stability,chemical stability and narrow spectral emission peak and long life which have become the focus and hotspotin the field of luminescence recently.At present,the problems of rare earth upconversion of nanomaterials include:(1)the controllable morphology andcrystal structure of nanomaterials;(2)the realization of nanomaterials upconversion luminescence optimization under the condition that nanocrystalline phase structure does not change;3)to explore the size regulation of rare earth doped upconversion luminescence nanocrystals to achieve the application on biomedical detection.In view of the above problems,we use the modified solvothermal method to prepare the upconversion luminescent nanomaterials with uniform particle size,good control of morphology,strong dispersibility and high luminescence intensity.The effects of heterogeneous ion doping on the morphology and particle size of nanomaterials and the optimization of optical properties were studied in detail.The main achievements of this paper are as follows:(1)The controlled of NaGdF4:Yb3+,Er3+ crystal structure and nanomaterial morphology was carried out for the first time by heterogeneous ion Mg2+ doping,and the mechanism of unequal ion doping was analyzed in detail.The results show that with the increase of doping concentration of heterogeneous ion Mg2+,the crystal shrinks slightly due to the decrease of the interplanar spacing.When the concentration reached as high as 60mol%,the limit is reached and the inside of the crystal begins to expand.At the same time,with the change of heterogeneous ion Mg2+doping concentration,the morphology of NaGdF4:Yb3+ and Er3+ were up-regulated by the mixed hexagonal nanospheres and nanorods.Regulation of the hexagonal phase of nano-disk,the appearance of a very significant change occurred.(2)The effects of heterogeneous ion Mg2+ doping on the luminescent properties of NaGdF4:Yb3+,Er3+ on the upconversion luminescent nanomaterials were systematically studied.The mechanism of the upconversion luminescence intensity after heterogeneous ion Mg2+ doping was also discussed in detail.The results show that the upconversion luminescence intensity increases with the increase of heterogeneous ion Mg2+ doping concentration,and reaches the strongest when the Mg2+ doping concentration is 60mol%.When the doping concentration is too high,the concentration is quenched.Therefore,within a certain concentration range,Mg2+ doping is favorable for upconversion fluorescence emission.The main reason for the enhancement of the upconversion luminescence intensity due to the heterogeneous ion Mg2+ doping is the decrease of the symmetry of the crystal field,which leads to the increase of the 4f-4f transition probability in the electrons,thus enhancing the upconversion luminescence intensity.(3)The first-order one-dimensional perovskite nanomaterials NaMgF3:Yb3+,Er3+,Gd3+ were synthesized by the modified solvothermal method for the first time.The effects of heterogeneous ion Gd3+ doping on the particle size,morphology and luminescence of the perovskite-like nanomaterials were also investigated.The results show that the particle size and morphology of the nanoparticles change greatly with the increase of the heterogeneous ion Gd3+ doping concentration,and the upconversion luminescence intensity is improved at the same time.